/*整体字体，颜色*/
body {
    font-family: 黑体, serif;
    color: black;
}

/*超链接的颜色，取消下划线*/
a {
    color: black;
    text-decoration: none;
}

/*鼠标经过超级链接改变颜色*/
a:hover {
    color: black;
}

/*忽略内边距和边框*/
article {
    box-sizing: border-box;
}

/*居中，相对定位，阴影*/
.board {
    width: 800px;
    background-color: aqua;
    margin: 0 auto;
    position: relative;
    box-shadow: 3px 3px 8px blue;
}

/*行高，底边框*/
header {
    height: 30px;
    line-height: 30px;
    border-bottom: 1px solid black;
}

/*左浮动，左外边距*/
.header_left {
    float: left;
    padding-left: 10px;
}

/*右浮动，文字居右，右内边距*/
.header_right {
    float: right;
    text-align: right;
    padding-right: 10px;
}

/*上外边距，居中*/
.danceMan {
    margin-top: 9px;
    text-align: center
}

/*字号，文字居中，行高*/
.screen {
    font-size: 50px;
    text-align: center;
    line-height: 90px;
}

/*忽略内边距和边框，左内边距，上内边距*/
.bar {
    height: 50px;
    box-sizing: border-box;
    padding-left: 500px;
    padding-top: 15px;
}

/*轮廓，相对定位，忽略内边距和边框*/
.progress {
    width: 200px;
    height: 20px;
    background-image: linear-gradient(to right, white 100px, aqua 125px, white 150px);
    outline: 2px solid black;
    box-sizing: border-box;
    position: relative;
}

/*圆角，绝对定位*/
.ball {
    width: 20px;
    height: 20px;
    background-image: radial-gradient(circle at center, white 1%, blue);
    border-radius: 50%;
    position: absolute;
}

/*居中，文字居中，上内边距，下内边距，圆角，边框*/
.keyboard {
    height: 30px;
    width: 600px;
    margin: 0 auto;
    text-align: center;
    padding-top: 10px;
    padding-bottom: 10px;
    border-radius: 20px;
    border: 2px solid black;
}

/*上外边距，下外边距，文字居中，行高*/
footer {
    height: 70px;
    margin-top: 10px;
    margin-bottom: 10px;
    text-align: center;
    line-height: 50px;
}

/*左右外边距，文字颜色，边框，圆角，字号，字间距，*/
footer button {
    background-color: white;
    margin: 0 30px;
    color: red;
    border: 2px solid black;
    border-radius: 10px;
    font-size: 18px;
    letter-spacing: 2px;
}

/*文字颜色，指针样式*/
footer button:hover {
    background-color: red;
    color: black;
    cursor: pointer;
}

/*八个按键：内联块，左右外边距，字号*/
div {
    display: inline-block;
    margin: 0 10px;
    font-size: 30px;
}

/*当方向键敲击正确时的文字颜色*/
.ok {
    color: red;
}